1. Field of the Invention
The invention relates generally to a method and apparatus for pulverizing a formation including useable raw materials such as an ore, coal or the like using a high speed projectile accelerator to hurl projectiles at the formation to breakup or pulverize a portion of an exposed surface of the formation.
More particularly, the invention relates to an apparatus for hurling one projectile or a plurality of projectiles at an exposed surface of a formation including a projectile car mounted on a track having two parallel rails, where the car includes a trapped field magnet and the track includes a plurality of electromagnets that can be turned on and off as the car moves down the track accelerating the car to a desired velocity. The apparatus also includes a stop assembly at its distal end designed to engage and nearly instantaneously stop the forward motion of the car expelling the projectile or the projectiles disposed in a projectile holder on the car. If the distal end of the apparatus is positioned adjacent a surface, then the projectile would impact the surface breaking or pulverizing the surface. The invention also relates to a method for breaking up or pulverizing a surface using the apparatus of this invention. In one embodiment, the apparatus comprises a superconducting linear motor.
2. Description of the Related Art
The mining industry has a significant need for an apparatus and method to breakup large rock sections loosened during mining operations such as blasting or other means. These rock sections can be up to 30 cubic meters in volume, and require break up into smaller pieces for transport out of the mine. Several approaches have been tried including: (1) additional blasting—this is not necessarily cost effective due to the need for drilling new set-charge holes, setting new charges, evacuating the mine and removing the residual gas; (2) steam/compressed air hammers—this requires a source of steam or compressed air and is limited as to hammer size and velocity; and (3) rf induction heating to fractionate—this requires water porosity of the rock structure, large and inefficient rf transmitters and safety procedures to protect against high levels of rf radiation. To pulverize a 30 cubic meter section of rock, energy of approximately 1 Mjoule is required. As an example, for a projectile launcher, this would require a projectile of approximately 1,000 kg at a speed of about 33 meters/sec (about 75 miles/hr). These requirements show the inadequacy of using a steam/compressed air hammer approach to break rock.
Electromagnetic motors have been described for the acceleration of a mass for warfare applications as in a rail gun in U.S. Pat. No. 5,078,043 (column 5) which patent is incorporated herein by this reference. The inclusion of superconducting material to a rail gun has also been described in U.S. Pat. No. 4,901,621 (column 2), which patent is incorporated herein by this reference.
There is a need, therefore, for a system (such as an electromagnetic launch system) to accelerate a projectile to the required speed over moderate lengths compatible with mine dimensions and mine operations and cause pulverization of rock with the projectile.